Headcanons/personal interpretations of these three duos :o)
Bash and Dash are kinda new ones here and I'm only recently trying to draw them out. They both have a hivemind state which they can enter and leave under their own will, though theoretically this can also be forced (but unwanted) by messing with their programming.
Bill and Ben are just. well. Bill and Ben. What more could you ask for. The only thing they likely wouldn't have a rampage at is a fossil collection or museum. Thanks, Marion, you tamed these beasts in some respect.
Been writing a lot for Donald and Douglas as well (unsurprisingly). Douglas also likes to go to Donald for emotional support, especially given he was at risk for being scrapped. Douglas is also usually calm and level-headed while Donald can be impulsive and quick to react or come to conclusions. Very defensive for the people and things he loves too.
Douglas originally took drawing as a way to feel better about his situation with scrap, and is now pretty good with environmental art and still life sketching in particular. I like to think he also does commissions but also draws a lot with Donald because again he can't draw /lh